Steam compressor comprising a dry positive-displacement unit as a spindle compressor

ABSTRACT

The invention relates to a spindle compressor designed as a twin-shaft rotary displacement machine for delivering and compressing flow media, particularly steam. It comprises a pair of spindle rotors in a compressor housing (1) comprising an inlet collecting space (11) and an outlet collecting space (12). The centre distance of the pair of spindle rotors is at least 10% longer on the inlet-side end than on the outlet-side end. Each of the two spindle rotors (2, 3) is driven by an electric motor (18, 19), and an electronic synchronisation controls the electric motors (18, 19) such that the spindle rotors (2, 3) rotate in a contact-free manner.

Cyclic processes are preferably described on the basis of Carnot's theorem, with heat output and heat absorption as well as a compressor as drive for the circulation medium in the gaseous phase. Cyclic processes are used very frequently and have become indispensable in our daily lives. These processes include clockwise and anticlockwise Carnot processes, with desired/targeted heat absorption to fulfil a cooling task (in the refrigeration and air conditioning field) or with desired/targeted heat output to fulfil a heating task (keyword “heat pump”) with heat exchangers for heat absorption and heat output. For the movement of the circulation medium, a drive in the form of a compressor for the circulation medium in its gaseous phase is generally required. Firstly, the circulation medium and its specific properties is critical. There are various artificial circulation media (generally chemically produced, such as HFCs and HFOs) and natural circulation media (such as ammonia, propane, propylene, isobutane, ethane.

Water, however, is irrefutably ideal as a circulation medium because of its general availability and the fact that it is completely non-toxic, can be safely used at low pressures in the form of steam, meets even the most stringent of guidelines and safety regulations, is resource-friendly, environmentally friendly, low maintenance, efficient and practically without any risk potential (incombustible, non-explosive, uncritical).

The challenge lies with the compressor, because in the working pressure range of a few mbar not only are enormous flow-rate volumes required, but also very high pressure conditions. This results in incredibly difficult compression conditions, in particular due to high temperatures, especially since the isentropic exponent for steam in this pressure range is quite high at about 1.327; by way of comparison, modern refrigerants lie in the region of just over 1.1 with correspondingly moderate temperature increases in the compressor.

The task of steam compression is nowadays performed by turbo compressors, but, in order for them to cope with the high pressure conditions, the compression must be performed in several stages with simultaneous intermediate cooling. Their fundamental characteristic weakness as turbomachines is that they allow only moderately satisfactory temperature and pressure conditions. If there were a more efficient compressor solution here, steam would be a significant advancement as a circulation medium because of its enormous advantages.

The object of the present invention is to provide the compression of (preferably) steam in the known working field and pressure range, which is generally referred to as a rough vacuum, by a positive-displacement machine which handles the desired pressure differences and the large p/p pressure conditions with the typically steep characteristic curve for a positive-displacement machine (i.e. pressure values over volume flow with the corresponding working points), wherein this machine must be completely dry running (no operating fluid) and should have a total efficacy for the entire system that is better for the entire field of application as compared to current turbo compressors, so that the user requirements in the field of refrigeration and in heat pumps as well as other (Carnot) cyclic processes are better met, especially in terms of a greater pressure range.

This object of compressing steam at pressures below atmospheric pressure (preferably between 6 mbar and 300 mbar, i.e. in the classic rough vacuum region) in a power range of less than 1 kW to well over 100 kW as refrigeration cycle power for refrigeration technology (i.e. industrial refrigeration, commercial refrigeration and building air conditioning) or as heat pump cycle power [the required compressor power is lower in accordance with the “COP” ^((as example)) value] is achieved in the form of a 2-shaft positive-displacement machine according to the spindle compressor principle with a gas inlet chamber (11) and a gas outlet chamber (12), wherein the centre distance between the spindle rotors on the gas inlet side (11) is greater than on the gas outlet side (12) and thus results in a crossing angle alpha, which is preferably between 3 and 25 angular degrees, in such a way that the features described below are provided:

The features according to the invention are:

-   1) electronic synchronisation, since each spindle rotor (2 and 3) is     driven by its own drive motor (18 and 19), each drive motor having     its own FU (22 and 23), each with its own measuring system (20 and     21) for detecting the rotary angle position, and an FU control unit     (24), which ensures that these drive motors (18 and 19) via their     own frequency converter (22 and 23) are driven at a corresponding     speed, such that the spindle rotor pair (i.e. 2 and 3) can work     without contacting one another. The cooling fluid supply (9.2 and     9.3) to the cylindrical evaporator cooling bore (6) of each rotor is     then provided additionally through the hollow shaft of the relevant     drive, the bearings (10) then preferably being formed as     grease-lubricated-for life hybrid bearings or all-ceramic bearings     (or even as magnetic bearings). -   2) cylindrical evaporator cooling bore (6) as a “rotating cylinder     evaporator” for automatic cooling self-balancing, since the water to     be evaporated, as spindle rotor cooling fluid under the pressure p₀*     and the temperature t₀* [these values with certain technical     deviations, such as pressure losses, temperature increase due to     unavoidable heat transfers], is diverted from the circuit of FIG. 2     and, in the cylindrical evaporator cooling bore, by the rotary     centrifugal forces, inevitably always goes during operation exactly     to where it is currently most urgently required for the current     working point, wherein the cylindrical evaporator cooling bore     (preferably) has the following features in accordance with the     following explanation:     -   A “rotating cylinder evaporator”, which is the design of the         internal cooling of the spindle rotors in accordance with the         invention, has the conceivably most favourable heat transfer         properties for the problem addressed by the present invention,         because the best-possible heat transfer is consistently achieved         as a result of the centrifugal forces, since the heavy liquid         parts in the rotating cylindrical evaporator cooling bore         constantly displace the lighter gas components from the heat         transfer surfaces in order to evaporate again immediately, so         that the next liquid parts for the heat transfer thus reach the         rotor material for the desired heat transfer, and additionally         at the same time, still in the rotor longitudinal axis direction         due to identical cylindrical radii values, the liquid parts to         be evaporated are always displaced by centrifugation to the         location where, due to the greatest evaporation, there is also         the greatest need for heat dissipation, because in the rotor         longitudinal axis direction different power distributions are         provided for each operating point, so that, at the known high         evaporation enthalpy differences with low (see values in FIG. 9)         cooling fluid supply, the most efficient possible heat         dissipation during the compression is achieved, so that in         accordance with FIG. 8 the compressor line from         to         is advantageously steep and clearly is better for the compressor         than an isentropic profile.     -   The following features apply for the cylindrical evaporator         cooling bore:     -   a) Cylindrical evaporator cooling bore (6) of radius R_(C) along         the length L_(C) with the spindle rotor positive-displacement         profile length L_(R), said cylindrical evaporator cooling bore         preferably beginning between positions E and S in the inlet         region and preferably going beyond the outlet end at L, so that         the values for L_(R) and L_(C) are comparable (approximately         equal). The cylindrical evaporator cooling bore (6) is designed         as an “inner structure” preferably via cooling fluid guide         grooves (16), cooling fluid distributor overflow grooves (17)         and support points (7).     -   b) The cylindrical evaporator cooling bore (6) should be as         cylindrical as possible (i.e. deviations well below 1%), wherein         for example manufacturing tolerances in the R_(C) values are         preferably set such that deviations tend to lead to larger R_(C)         values in the direction of the outlet (i.e. in the region of         position L).     -   c) Spindle rotor made of an aluminium alloy is rotatable         conjointly with the “inner structure” already manufactured,         wherein to form this “inner structure, the cylindrical         evaporator cooling bore (6), preferably formed by cooling fluid         guide grooves (16) with radius R_(C) and comprising multiple         support points (7), is preferably pressed on to the supporting         steel shaft at these support points, for example by component         temperature difference, by joining the warmer aluminium rotor         body to the cooler steel shaft and then making this a fixed         connection with temperature equalisation, wherein only then is         the gas-conveying “external thread” (31) produced, so that the         wall thicknesses w can be minimised in order to improve the heat         conduction through shorter paths in the event of dissipation of         the compression heat.         -   The groove bottom of the cooling fluid guide grooves (16) is             preferably designed such that the groove base surfaces are             formed with inclination angles ψ(z), which, depending on the             z-position in the rotor longitudinal axis direction, which             is usually referred to as the z-axis, is preferably in the             range         -   170°≤ψ(z)≤180° depending on the position z in the rotor             longitudinal axis direction, so that the distribution of the             cooling fluid (9) with smaller amounts of cooling fluid             (because there is always only so much cooling fluid supplied             that the total energy balance at the particular working             point gives the highest efficiency) along the rotor axis is             improved by the smaller filling cross-sections depending on             the current amount of cooling fluid, appropriate for the             operating point. The cooling fluid guide grooves are             designed here similarly to a thread, preferably with the             greatest possible pitch, for example as in the case of the             gas-conveying external thread (31), in order to thus perform             the task of minimising the amplification of the residual             unbalance resulting from the introduction of the cooling             liquid (9.2 and 9.3) into each rotor (because all liquid             collects in the rotating system at the greatest possible             distance from the current rotation point and thus amplifies             the residual unbalance), which is very poorly fulfilled for             example with a pitch of zero of the cooling fluid guide             grooves.         -   This effect of the residual unbalance amplification is used             in accordance with the invention simultaneously to minimise             the amount of cooling fluid supplied (9.2 and 9.3) per             rotor, since vibration sensors (as used for example for             bearing monitoring) display this residual unbalance             amplification by an excessively large amount of cooling             fluid in the corresponding rotor system, wherein, thanks to             different rotor speeds (the 2t rotor always rotates 1.5             times faster), it is precisely determined at which rotor the             amount of cooling fluid is too high, so that the control             unit (25) can make the adjustment that is correct in the             present case (in the sense of the minimum required amount of             cooling fluid) via the regulation members (38).     -   d) To compensate for deviations and to ensure the most reliable         possible distribution of the water to be evaporated in the rotor         longitudinal axis direction at the cylindrical evaporator         cooling bore (6), there are additionally also undersized cooling         fluid distributor overflow grooves (17) in the bottom of the         cooling fluid guide grooves (16) of radius R_(C), which         undersized cooling fluid distributor overflow grooves are         arranged at a distance from the rotor axis of rotation which is         greater than the R_(C) value, but at the same time have such a         small cross-section that the water contained therein goes beyond         the cross-section of these cooling fluid distributor overflow         grooves (17) and wets the bottom of the cooling fluid guide         grooves (16) of radius R_(C).         -   The embodiment of the cylindrical evaporator cooling bore             (6) is of course described here merely by way of example             with support points (7) and cooling fluid guide grooves (16)             of radius R_(C) and with cooling fluid distributor overflow             grooves (17). Of course, other embodiments are also             conceivable here.     -   e) Addition of cooling fluid (9) in particular to the rotors         always limited to the minimum amount, possibly even only         sporadically and in pulses, both to avoid critical unbalances         and to minimise the amount of diverted cooling fluid flow (9) in         the sense of maximising the overall efficiency, because this         cooling fluid flow (9) lacks the actual circulation medium (28)         in the evaporator (35) in the event of the heat absorption. The         cylindrical evaporator cooling bore (6) in each spindle rotor         thus receives only so much water (with a tolerance of for         example+1%, which is conventional in this field) as is currently         needed for evaporation at the particular working point.     -   f) This minimisation of the cooling fluid flow amount (9) is         achieved for example by measurement via known and simple         vibration sensors (for example for rolling bearing monitoring)         for determining the degree of filling in the particular         cylindrical evaporator cooling bore (6) per spindle rotor (2 and         3), because an increased amount of water in the particular         cylindrical evaporator cooling bore (6) will amplify the         residual unbalance in the rotating system, and, thanks to         different speeds of the spindle rotors (the 2-toothed spindle         rotor rotates faster than the 3-toothed spindle rotor by a         factor of 1.5), as unbalance excitation can be associated with         the rotation system of the 2-toothed or 3-toothed spindle rotor,         so that the cooling fluid amount (9.2 and 9.3) is adjusted in         accordance with the minimum amount. Thus, only as much water as         is currently needed for evaporation in the current operating         point is supplied.         -   Of course, other approaches for minimising the cooling fluid             flow amount (9) can also be used. -   3) Steam outlet (14) from the cylindrical evaporator cooling bore     (6) for each spindle rotor, characterised in that each cylindrical     evaporator cooling bore (6) is formed with the radius R_(C2) or     R_(C3) and the steam outlet (14) is realised via transverse bores,     which are preferably arranged balanced in relation to each other,     after a step over a radius R_(D2) or R_(D3), wherein R_(D2) and     R_(D3) at the particular spindle rotor is slightly smaller (i.e. a     few mm, for example 2 to 5 mm) than the corresponding R_(C2) or     R_(C3) value of the corresponding cylindrical evaporator cooling     bore (6). -   4) Cooling fluid injection (33) in the working space for selectively     influencing the conveyed gas temperatures in the working space, i.e.     the space between the inlet collection chamber (11) and outlet     collection chamber (12). -   5) With regard to the heat dissipation for the working space     components, i.e. the pair of spindle rotors according to (2 and 3)     and the compressor housing (1), said heat dissipation being so     significant for the dry-running machine, two stages are to be     distinguished:     -   A) Basic stage with component heat dissipation: The heat         dissipation for the working space components can be used as a         basis for safeguarding and ensuring at all times that play         reduction (which generally leads to the failure of the         compressor, or a “crash”) between the working space components         is reliably avoided at all operating points:         -   This indispensable requirement is already achieved with             small amounts of cooling fluid (9) by for example reducing             the heat dissipation for the compressor housing (1), i.e.             throttling the corresponding cooling fluid flow (9.1) with             minimal cooling fluid flow amounts (9.1), so that the             thermal expansion of the working space components does not             jeopardise the play situation.         -   At the same time, in the case of this basic stage for             component heat dissipation, it must be ensured that the play             values (i.e. the distance values between the working space             components) remain within a certain range, i.e. since the             minimum play values during operation are about 0.03 to 0.09             mm (depending on the overall size, in large machines             with >150 mm centre distance the values lie above 0.05 mm),             the basic stage for component heat dissipation during             operation should be configured so that not only is the             aforementioned play reduction reliably avoided (as             indispensable mandatory requirement, said minimum play             values receiving a safety margin of about 20% to 50%), but             also the play values for other operating points, due to the             different thermal expansion behaviour of the components,             compared to these lower play values are greater by a factor             of 2 to at most a factor of 3, which is to be ensured by             this basic stage for component heat dissipation during             operation and is now attainable for the first time with a             dry-running machine via the control unit (25) (previously             only feasible with wet rotors).     -   B) FCT stage with component heat dissipation: (FCT stands for         Final Compression Temperature, i.e. the temperature of the         conveyed medium at the end of compression and usually the         highest gas temperature, the FCT usually being determined in the         outlet chamber (12).) The power demand during the compression of         a volume (and that's exactly what happens in the present         compressor provided in the form of a “positive-displacement         machine”) is generally reduced, thereby improving the efficiency         (efficacy) of the compression, if the temperature increase in         this volume during the compression process can be minimised. The         necessary heat dissipation during compression is known to depend         also on the temperature difference between the gas in this         volume and the surrounding heat-dissipating surfaces of the         working space components, and also in addition the heat transfer         coefficients (known in the case of steam to be quite high         values) and the heat conduction (which is why an aluminium alloy         is preferably used as material for the spindle rotors). Thus,         the cooler the surfaces of the working space components can be         kept via the cooling flow, the better is the heat dissipation         during compression and the lower is the temperature increase of         the conveyed gas in the conveyed and compressed working chamber         volumes, hence the compressor working line becomes increasingly         steeper—shown by way of example in accordance with FIG. 8         between the points         and         .         -   This generally achieves a reduction in the power demand for             the compression and thus an improved (higher) efficiency. -   6) Depending on the application-specific requirements and according     to the corresponding parameter design (i.e. crossing angle, rotor     length, inlet and outlet centre distance, head and root radii values     per end-face section, gradient and number of stages as well as     design of the “inner structure” and the spindle rotor pair     cross-section) for the compressor design according to the invention,     the cooling fluid flow (9) for heat dissipation for the working     space components can be described by the following two approaches:     -   Diverted cooling fluid partial flow: (as shown by way of example         in FIG. 2 as cooling fluid flow (9)) As shown in FIG. 2 by way         of example, the cooling fluid flow (9) is diverted from the         actual circuit as a partial flow, which is considered a         preferred solution because it enables the maximum heat         dissipation with the cylindrical evaporator cooling bore (6)         during compression. The only disadvantage is the fact that this         diverted cooling fluid flow (9) is removed from the main flow         and thus is missing when the core task is performed in the field         of refrigeration technology, i.e. the heat absorption in the         evaporator (35). In heat pumps, when the heat output in the         condenser (36) represents the core task, this diverted cooling         fluid partial flow is not missing from the circulation medium         (34).         -   Thus, the following principle applies: If, in a manner             specific to the application, the advantage by reducing the             compression temperatures in the mentioned FCT stage during             component heat dissipation is greater than the disadvantage             due to the reduced amount of cooling fluid (28) through the             evaporator (35), then the diverted cooling fluid flow (9)             should be realised by the cylindrical evaporator cooling             bore (6) as shown by way of example in FIG. 2, wherein the             amount of diverted cooling fluid flow (9) must be adapted in             a targeted and controlled manner to the particular             requirement profile in the sense that, in each situation and             regulated by control unit (25), only such an amount is             diverted as cooling fluid flow (9) that the compressor             efficiency improvement by the heat dissipation brings more             advantages in respect of the overall energy consideration             than the previously described disadvantage, with associated             additional effort by the diverted cooling fluid flow. If             this approach is no longer achievable for some applications,             then the “separate cooling water flow” described below             applies.         -   Separate cooling water flow: (as shown by way of example in             FIG. 6.d) If the advantage by lowering the compression             temperatures in the mentioned FCT stage during component             heat dissipation for the particular application is less than             the disadvantage caused by the reduced cooling fluid amount             (28) through the evaporator (35), then a separate cooling             water flow as shown according to FIG. 6 with the internal             rotor cooling described in PCT/EP2016/077063 should be             realised, whereby it is ensured that play reduction between             the working space components is avoided definitively and             independently of the circulation medium.         -   The benefit that the separate cooling water flow for             avoiding the play reduction somewhat lowers the compression             temperatures quasi incidentally is indeed included.             Naturally, the available cooling water temperatures are             critical, and thus it is not possible to provide a generally             valid guideline, and therefore a decision must be made             separately for each specific application. Thus (in simple             terms) the available cooling water temperatures will be             different in a hot environment (countries near the Equator)             than in cold regions at any given time of the year (Siberia             in winter).         -   Delayed evaporation:         -   If evaporation of the cooling fluid (9.2 or 9.3) should not             occur in the cooling fluid guide grooves (16) due to the             enormous acceleration values, then it is further proposed in             accordance with the invention that this cooling liquid             (heated in the meantime by absorption of the compression             heat) is drawn off by pitot tube (as described for example             in DE 10 2013 009 040.7 or in 10 2015 108 790.1), has a             higher pressure than p_(C) because of the high kinetic             energy, and consequently at a point after the compression             process, for example in the outlet collection chamber (12),             is fed back to the circuit, where this liquid is then             evaporated and can absorb heat again task-specifically, the             amount of cooling fluid then being adjusted so that the             overall efficacy is improved.     -   In any case, the correct cooling fluid amount (in terms of         efficiency and unbalance minimisation) for the particular         operating/working point of the control unit (25) is regulated,         wherein the corresponding data are stored in this control unit         (for example in accordance with appropriate process simulation).         “Trial-and-error” is also used as a self-learning process,         wherein the system itself tries out variations and uses the         reactions (i.e. energy demand and net output) to itself         determine the setting with which the highest efficiency is         achieved for the current working point. This approach can also         be referred to as an “action” approach. Therefore, it must be         decided on a case-by-case basis which of these approaches best         solves the application-specific task. -   7) Adaptation of the inner volume ratio to the current operating     point in accordance with the invention by additional partial outlet     openings (15), which preferably open in a spring-loaded manner and     allow a partial gas flow to escape from the particular working     chamber into the outlet collection chamber (12) when, in this     working chamber approaching the outlet, the pressure is greater than     the pressure in the outlet collection chamber (12), so that in the     working chamber a harmful over-compression (adversely affecting the     efficiency) is avoided.     -   The inner volume ratio (i.e. the quotient of the working chamber         volumes between inlet and outlet), as “iV value”, must be         adapted in the best possible manner to the current operating         point for the most efficient (i.e. energy-saving) compression,         in order to avoid harmful over- or under-compression. During         operation, the iV value can be adapted in accordance with the         invention by means of additional partial outlet openings (15),         but must first be determined via the spindle rotor pair design.         The iV value is influenced fundamentally by the following 3         variables:         -   Centre distance between the rotor axes of rotation (variable             due to crossing angle alpha between the rotor axes of             rotation and larger at the gas inlet (11) than at the gas             outlet (12).         -   Ratio of the rotor head radii to centre distance in the end             section as μ(z) value, using the equations below at each             point z in the rotor longitudinal axis direction, wherein in             addition the root angle γ_(F2) is selected purposefully to             maximise the nominal pumping capacity, the exact procedure             also being described in detail below.         -   Gradient in the rotor longitudinal axis direction (also             determines the number of stages at the same time, i.e. the             number of closed working chambers between inlet and outlet),             wherein the rotor length is known to be as long as possible             up to the critical bending speed. When determining the             mentioned rotor pair parameters, the “inner volume ratio” as             “iV value” (i.e. quotient of the ^([larger]) inlet to the             ^([smaller]) outlet working chamber volumes) should thus be             configured in accordance with the isentropic exponent of the             conveyed medium, the compression process, in particular in             respect of the heat dissipation during the working chamber             volume change (i.e. the compression), and the desired             compression ratio (i.e. the quotient of outlet pressure to             inlet pressure).         -   By way of example, this relationship is presented with             reference to the values mentioned in FIG. 7:         -   The conveyed gas (steam) is to be compressed, for example,             from 7.0 mbar to 95.9 mbar, resulting in a compression ratio             of:

95.5 divided by 7.0=13.7.

-   -   -   Only in the case of isothermal compression (i.e. no             temperature change during the compression) would an inner             volume ratio of 13.7 be implemented here as well.         -   Due to the increase in temperature in the working chamber             during the “polytropic” compression, in accordance with the             invention, starting from the present isentropic exponent for             steam in this range of about 1.327, an iV value of about 10             will be provided by the intensive heat dissipation during             the compression via the cylindrical evaporator cooling bore             (6), in order to avoid both over- and under-compression.         -   This iV value as a change in the working chamber volumes             which results from the multiplication of the relevant             spindle rotor pair cross-sectional areas and the extent in             the rotor longitudinal axis direction (generally ascertained             via the profile gradient), is now technically realised in             accordance with the invention by:

    -   a) varying the spindle rotor pair cross-sectional area in each         end-face section (shown by way of example in simplified form in         FIG. 3 as a planar sectional view) in the rotor longitudinal         axis direction, wherein the inlet-side rotor pair cross-section         is larger than the outlet side rotor pair cross-section. This         cross-sectional change at the spindle rotor pair is now achieved         by:         -   changing the centre distance via the crossing angle alpha of             the two rotor axes         -   changing the profile tooth height via the mentioned μ(z)             value at each z position

    -    This change in the cross-sectional areas at the rotor pair due         to the change in centre distance and μ(z) value results in a         “iv.aμ value”) (cf. FIG. 9), wherein the working chamber extent         must be considered. In this case, it must be ensured that a         cylindrical evaporator cooling bore (6), wherein each spindle         rotor has its own R_(C) values, is provided alongside minimum         wall thicknesses w in the supporting root main body (32) whilst         simultaneously taking into account the different critical         bending speeds, as presented by way of example in FIG. 9.

    -   b) changing the profile gradient (generally referred to as m) in         the rotor longitudinal axis direction: By changing the profile         gradient, a “iV.m value” (cf. FIG. 9 as an example) is created,         which is usually significantly (more than a factor of 3) greater         than the “iV.aμ value”, wherein the number of stages (i.e. the         number of complete working chambers between inlet and outlet)         over the rotor length L_(R) still permissible from a         bend-critical viewpoint whilst observing the “mesh limit” (what         tooth gap depth still can be produced relative to the tooth gap         width) must be taken into account.         -   Of course, these two changes act simultaneously and             multiplicatively in the rotor longitudinal axis direction in             order to arrive at the desired overall iV value, in this             example=10, which is shown by way of example in FIG. 9.         -   It is known that the higher the total iV value is, the more             intense is the heat dissipation during compression, wherein             a reduction in the compression temperatures generally leads             to an improvement in the compressor efficiency (i.e.             increase in efficacy).         -   Now, if the working point deviates from these mentioned             pressure values, the additional partial outlet openings (15)             ensure the ideal adaptation to the current working points             and thus an efficient compression process at any time.

-   8) Each spindle rotor (i.e. the aluminium part, which sits     non-rotatably on the steel shaft) consists of 3 regions:     -   a) external gas-conveying thread (31) The external gas-conveying         thread (31) is preferably made only after the connection, for         conjoint rotation, to the steel shaft, in order to minimise the         size of the root main-body wall thickness w.     -   b) root main-body wall thickness w (32) to minimise resistance         to heat dissipation and to maximise heat dissipation         accordingly.     -   c) “inner structure” consisting of cylindrical evaporator         cooling bore (6) with support points (7) and lateral supports         which are to be sealed off on the outlet side=for example by         O-ring) and inlet-side steam outlet (14) for the cooling fluid         evaporated in the cylindrical evaporator cooling bore (6) from         the cooling fluid flow (9) per working space component.

-   9) By way of example, 4 positions in the rotor longitudinal axis     direction for describing the spindle rotor design according to the     invention are mentioned (of course, there may also be more or fewer     positions, nevertheless the spindle rotor design according to the     invention can be well described, wherein in FIG. 1 and FIG. 4 as     well as FIG. 5 the following is true for the following positions     from the gas inlet (11) to the gas outlet (12):     -   In this case, the following definition applies to each position         in the rotor longitudinal axis direction (usually designated as         z). “μ(z) value” per spindle rotor in the profile design at each         z position for the gas-conveying external thread (31) of each         spindle rotor:

$\begin{matrix} {{R_{K\; 2}(z)} = {{\mu_{2}(z)} \cdot {a(z)}}} \end{matrix}\mspace{14mu} \text{or:}\mspace{14mu} \begin{matrix} {{R_{K\; 3}(z)} = {{\mu_{3}(z)} \cdot {a(z)}}} \end{matrix}$

-   -   In addition, the root angle γ_(F2) is purposefully selected by         making it greater than 90° when μ₂>0.6, wherein the head         cylinder width b_(K2)(z) does not fall below a selected limit         value, for example 5 mm.     -   a) Position E:         -   on the rotor-pair end inlet side with the greatest distance             between the spindle rotor axes of rotation as a_(E) value         -   in accordance with the invention with cylindrical flattened             portion (27) on the inlet side of the 2-toothed spindle             rotor (2) over the radius R_(KE2) in order to expand the             maximum/highest rotor head speed to a larger spindle rotor             area, wherein preferably a radii-like transition, shown in             FIG. 2 by way of example as “R·tan”, allows the uniform             transitions.     -   b) Position S: (can also be represented as a range over several         z-values)         -   with the largest μ-value preferably such that the inlet             working chamber receives the largest possible volume without             violating the stated boundary conditions (i.e. cylindrical             evaporator cooling bore, wall thicknesses at the supporting             root main body (32), blowhole freedom, critical bending             speed etc.), wherein the μ-value according to FIG. 3 and the             equations given for each z position in the rotor             longitudinal axis direction are purposefully realised, as             shown by way of example in FIG. 9.     -   c) Position V: (can also be represented as a range over several         z-values)         -   wall thickness adapted in accordance with the tooth height             with reduction of the cross-sectional area in order to             realise the internal compression with simultaneous good heat             transfer properties over the supporting root main body (32).     -   Position L: (can also be represented as a range over a plurality         of z-values) preferably as a cylindrical end, which is         expediently designed to protrude beyond the end of the external         thread into the outlet chamber, as shown by way of example in         FIG. 1. As an overview table, the preferred specific values for         these positions are shown by way of example in FIG. 9. The         emphasis is exemplary, because both other positions and also         other values can be realised. The parameters mentioned in this         FIG. 9 merely show a meaningful embodiment illustrating the         “spirit” of this invention. In this case, each position can         certainly also be implemented as a z-range over several z-values         in the rotor longitudinal axis direction and not just as a         singular z-position.

-   10) The crossing angle alpha according to FIG. 5 between the two     spindle rotor axes of rotation is provided in combination with the     particular μ(z) value in the rotor longitudinal axis direction such     that each rotor has a cylindrical evaporator cooling bore (6) with     minimal (i.e. in respect of the material strength matching the tooth     height in question) wall thicknesses w on the supporting root main     body (32) (for example, according to the above position descriptions     of E, S, V and L), while taking into account the (preferably)     blowhole-free rotor profile design of the gas-conveying external     thread (31) and bending-critical speed “appropriate to the specific     spindle rotor” (°*°) in accordance with the following point     regarding the critical bending speed and provision of the inner     volume ratio according to the embodiment previously described.     -   °*° “appropriate to the specific spindle rotor” means that, in         accordance with the speed differences between the two spindle         rotors, the 2-toothed spindle rotor rotating 1.5 times more         quickly has both a higher flexural rigidity and a relatively         lower rotational mass, so that the critical bending speeds are         reached by both spindle rotors equally.

-   11) critical bending speed ω_(critical) for the two spindle rotors     via their parameter design (i.e. in terms of diameter=stiffness)     such that

$\begin{matrix} {\omega_{\underset{2\text{-}{rotor}}{critical}} = {1.5 \cdot \omega_{\underset{3\text{-}{rotor}}{critical}}}} \end{matrix}\mspace{14mu} \text{with}\mspace{14mu} \begin{matrix} {\omega_{\underset{generally}{critical}} = \sqrt{\frac{c}{m}}} \end{matrix}$

-    critical bending speed generally as square root of rigidity (incl.     bearings) over mass.     -   To achieve high speeds, each rotor system in accordance with the         invention is embodied as a rotation unit (40), as shown by way         of example in FIG. 6b , this being of crucial importance because         the balance is provided for the complete rotation unit (40),         whereby the balancing quality is improved.     -   This is because it is well known that even well-balanced         individual parts, which are later assembled to form a rotation         unit which can no longer be balanced separately as a unit (which         is practically always the case with prior art 2-shaft         positive-displacement machines), in their sum then give a poorer         balance quality than the separately balanced and henceforth         unchanged rotation unit, as shown by way of example in         accordance with the invention in FIG. 6 b. -   12) Play adjustment between the spindle rotor and the compressor     housing via separator plates (26) by first introducing each spindle     rotor, during assembly, individually into the compressor housing (1)     until the spindle rotor heads contact the housing bore and then     pulling them out again and fixing them via the separator plates     (26), so that exactly the desired head gap value between the rotor     head and housing is given, as shown in FIG. 6c by way of example as     Δ2.1. -   13) The following rules must be observed for the bearings:     -   Since the bearings are only a single element in contact and         therefore subject to wear, the bearings must be designed with         particular care. Therefore, the following rules for the bearings         must be observed:     -   In the case of steam, the bearing forces (both axial and radial)         are very low and the main load is caused by the high speed,         which is why in bearing technology what is known as the n·d_(m)         factor is used as speed characteristic, i.e. the product of mean         bearing diameter [in mm] multiplied by the speed [in rpm=1/min],         wherein the machine tool construction under the keyword         “spindle-bearing” here provides precise design recommendations.         If this speed characteristic exceeds one million mm/min, special         emphasis must be placed on speed resistance and lubrication. The         rotor speed results from the maximum permissible rotor head         speed below supersonic for the conveyed medium in the working         area. The limit value for steam in the pressure range is         specified at about 400 m/sec, which is why in accordance with         FIG. 9 a value with sufficient safety margin is selected in the         table with 350 m/sec, by way of example. According to the         invention, the 2-toothed spindle rotor (2) is also flattened         cylindrically in the inlet region so as not to hit the speed         limit too early in this region, because in the outlet direction         the rotor head velocity drops rapidly due to smaller diameter         values (see FIG. 9, the table values).     -   For the present invention, the bearings are for         example/preferably to be constructed as hybrid spindle bearings         (e.g. of type XCB70) sealed on both sides with appropriately         adapted lifetime lubricant and distanced appropriately from the         conveyed medium via the working space shaft seals, wherein these         working space shaft seals, in addition to separation and defence         means (see ima catalogue from machine tool construction for         spindle seals), also have neutral collection/buffer chambers         (13) as protection as well as the imperative(!) avoidance of any         gas flow through the bearings, which invariably need a safe         bypass, i.e. a gas-permeable bypass (channels, holes) with         minimal flow resistances. Instead of the aforementioned hybrid         spindle bearings, of course, all-ceramic bearings are also         feasible, as well as magnetic bearings if appropriate, and even         water bearings. -   14) The evaporator cooling for the working space components can be     represented as a horizontal line with the pressure p₀* at t₀*     according to FIG. 8, as shown by way of example in FIG. 2: For     differentiation, the * are used, because this pressure can     definitely and specifically differ from the pressure p₀ at t₀ in the     evaporator (35), if advantageous according to the     application-specific process simulation. It is also possible to     perform the evaporator cooling for the working space components via     a separate refrigeration cycle. -   15) Instead of the rotor pairing with 2-toothed spindle rotor (2)     and 3-toothed spindle rotor (3) as “Tribivari”, other rotor pairings     are also conceivable (although probably less efficient), such as:     rotor pairing as “SynchroVari” according to DE 10 2016 004 048.3 as     well as the classic 2: 2-cycloid rotor pairing (but with blowhole) -   16) The control unit (25) satisfies the particular     application-specific requirements in that the control unit (25)     manages and intelligently regulates, controls and monitors the     entire system. All relevant data are stored in the control unit (25)     and are collected and evaluated. -   17) The displacement machine according to the invention, hereinafter     referred to simply as “Tribivari”, is designed as an intelligent     system, which is solved by the features and properties described     below, where the abbreviation “ES” stands for the “electronic motor     pair spindle rotor synchronisation” according to the invention. This     novel intelligence can be presented by the following special tools:     -   (self) diagnostic tools     -   regulatory tools -    The following somewhat more detailed explanations are intended to     facilitate comprehensibility, although there may inevitably be some     repetitions and “embellishments” under the consideration from     different perspectives, with slightly differing terms (due to the     different perspectives, which certainly improves the comprehension).

A compressor works in principle between the following two limits:

-   -   efficient compression (minimising internal leakage, suitable         π_(i) value, effective heat dissipation, etc.) as a soft limit     -   Avoidance of gap reduction (crash) as a hard limit     -   Challenge for these limits: (This applies especially for dry         runners)     -   A) individual for each individual machine (manufacturing         tolerances, assembly differences etc.)     -   B) change during the runtime (deposit formation, dirtying, wear,         etc.)     -   C) dependent on the particular operating point (in particular         pressure range, volume flow, etc.)     -   D) vary with changing ambient conditions (hotter, colder,         dirtier etc.)     -   Summary:     -   The more precisely the individual limits of each compressor in         its particular situation are known and useable(!) during its         service life, the better this system will be.     -   What can Tribivari do better than today's compressors?: Today's         compressors (in particular as dry-running machines) are designed         to survive the worst-case scenario, i.e.: At the other working         points they are inferior because of higher leakage.     -   Tribivari, by means of “PartCool”, manages at all times(!) the         thermal situation of all components for the compressor efficacy         and can thus adapt to “all” conditions with ongoing         self-diagnosis and Δ-compensation! (Δ stands generally for         deviations and differences)     -   “PartCool”=cooling water flow guided intelligently by CU for         each component, plus harmonisation of inner compr. ratio     -   The thermal situations of all components are finally known         individually(!) and at all times and are adjustable by setting         the relevant cooling fluid flows selectively by algorithm in the         CU.     -   How does Tribivari provide its individual°*° intelligence?:     -   °*° individual=for every machine in every situation &         environment at any time     -   check the k₀ speed** and continuously compare with stored value     -   measure flow resistance by Σpressure difference degradation as a         function of time     -   inverse cooling to determine the crash security for ΔT as a         temperature difference     -   measured value comparison with subsequent extrapolation     -   . . . etc. . . . .     -   The CU is used for the specific PartCool regulation thanks to an         algorithm with targeted compensation of deviations and         differences, which learns by comparison.     -   Tribivari knows at all times how far its own load can be driven         in each case     -   to: a) safely avoid a crash (gap reduction)     -   and b) to intelligently maximise the compression efficacy for         precisely this “situation”     -   incl. c) to learn independently by its own comparison(!):         -   What was good? What was bad?=>This leads to the relevant             optimum     -   plus d) by extrapolation as a prognosis with corresponding         notification “upwardly” (outside).         i.e.: Tribivari helps itself by fixing itself practically         single-handedly.

What is the new Tribivari CU “intelligence”? [CU=control unit]

Unlike the currently only “semi-mounted” (screws already worked beforehand) controllers, the intelligence of Tribivari is a conceptual part of this new compressor technology, since the entire operation is managed by the control unit individually (i.e. specifically to each Tribivari with its own tolerances and particular use conditions/deviations) under all conditions, including constant changes thereto, with independent self-diagnosis(!) and prognosis with ongoing adaptation to the process under various conditions (colder/hotter environment, poorer cooling, etc.). This is the new Tribivari intelligence.

Today's compressors can only adapt inadequately to the current process and changes thereto and to changing environmental conditions (e.g. hotter). Reasoning:

-   -   A) “oil-injected screws”=injected oil quantity (indispensable         due to internal leakage, heat dissipation and lubrication)         cannot be adjusted arbitrarily in respect of oil quantity and         oil temperature.     -   B) “dry-compressors”=they do not manage all(!) of the thermal         situation of their working space components and therefore have         only one good working point (minimum gap) for crash avoidance         (gap reduction) and otherwise work “unhappily” at extreme         speeds.     -   C) In addition, none of these machines can adapt their internal         compression ratio (i.e. between over-compression and         under-compression) to the current operating point (cf.         refrigerant compressor effort for housing slide)

Tribivari is fundamentally superior here in that it fulfils 3 features simultaneously:

-   -   Tribivari=dry PLUS eta PLUS μC What is key is the PLUS of these         features.     -   This is because Tribivari manages the thermal situation of all         working space components, as follows:     -   any time=the CU permanently monitors the compressor and always         regulates the cooling fluid flows via what is known as PartCool         (as described)     -   complete=both with regard to process and environmental         conditions as well as all appropriate working space components     -   flexible=different and changing conditions during the process         and in the surrounding environment are tolerated     -   comprehensive=via cooling fluid mass flow and cooling fluid         temperature suitable for any current situation and not only for         one working point, but always optimal for the entire working         area     -   synchronous=the working space components are always managed         synchronously (=always in step, no divergence)     -   efficient=always with appropriate heat dissipation (and not         according to the motto: “the more the better”, but in each case         as appropriate=intelligent!), the best polytropic exponent and         no over-/under-compression for desired pressure volume flow     -   intelligent=with own learning(!) algorithm with self-diagnosis         and prognosis, even forward-looking     -   Specifically with Tribivari:

-   a) monitoring and management of the thermal situation of all working     space components

-   b) so that thanks to ACTUAL gap differences, the inner leakage     (=entropy) can also be handled via the gap dimensions

-   c) always adjust the inner compression ratio appropriately with     additional partial outlet openings

-   d) optimise the magnitude of heat dissipation to the polytropic     exponent of the compression

-   e) and thus maximise the efficacy

-   f) adapt or monitor the temperature level in an application-specific     manner if necessary

-   g) to give the desired conveyed gas amount and the setpoint     operating pressure by rotor speed and cooling fluid adjustment.

What, among other things, forms part of the “Tribivari_CU-intelligence”?:

-   -   (better than the currently only “semi-mounted” FU intelligence         in the case of screws)

-   1) Play values Δ: =gap distances between the working space     components:     -   Δ2.1=2-t rotor from the housing     -   Δ3.1=3-t rotor from the housing     -   Δ3.2=rotors from each other     -   Δ as function ƒ(z) possible in rotor longitudinal axis direction     -   Δxy denotes integral for all gap distances

Purpose:

-   -   reliable avoidance of gap reduction (=crash),     -   knowledge of the size of the leakage gap (for highest efficiency         per working point)     -   . . . that's not possible today

-   1.1) Detecting the actual individual gap values (in particular with     regard to manufacturing tolerances and assembly differences) in each     AirEnd assembly via separator plates on the fixed bearing exactly     set for each(!) rotor according to:     -   a) for Δ2/3.1 by contact+withdrawal         -   ( . . . as an assembly-must per rotor, alas integral over l,             not in operation . . . )     -   b) for Δ2/3.1 by inverse cooling         -   ( . . . also in operation after the k₀ speed measurement,             PartCool division)     -   c) for all Δxy by k₀ measurement         -   ( . . . clear, with PartCool adaptation, also in operation             plus inverse cooling)     -   d) for Δ2/3.1 with hot rotors         -   ( . . . inaccurate temp. level/fluctuations/duration)     -   e) for all Δxy by spying         -   ( . . . barely accessible)     -   f) for Δ3.2 by electronic synchronisation ( . . . note: Δφ of         the emergency synchro-wheels is detected first)

-   1.2) Detecting the changes of these gap values during operation     according to A) to D) as ongoing conclusion regarding comparison of     measured values and/or k₀ speed and/or flow resistance and rotation     angle Δ with electronic synchronisation . . . =all with     interpolation and extrapolation

-   2) Self-diagnosis:     -   Evaluation by algorithm in the CU based on the individual gap         values according to 1) with determination of need for action         incl. tendency detection (prognosis) with intelligent analysis         plus vibration sensors (especially for bearing monitoring)

-   3) Adaptation to the process, especially in the case of process     changes:     -   (=much more than just today's speed adjustment) Adaptation to         the particular process and its process changes by evaluating the         differences in the algorithm and leading to actions=for example         PartCool adjustment

-   4) Adaptation to the environment, especially in the case of     environmental changes:     -   Adaptation to different and changing environmental conditions

-   5) Efficacy Optimisation:     -   always lowest possible energy consumption through optimal         cooling regulation     -   not just for a single working point (as before), but for the         entire area

-   6) Temperature control:     -   Compliance with desired limit temperatures (esp. sensitive         process gases)

-   7) Compression adjustment:     -   Change in internal compression ratio via additional partial         outlet openings (15) to avoid under- and over-compression

-   8) Purity of the conveyed medium:     -   Adaptation of the size of the secondary gas flow to the neutral         chamber per working area shaft seal

-   9) BASIS:     -   Simulation algorithm stored in the CU, fed by the individual gap         values and the current situation and correspondingly adapted         reactions, based on maps that are constantly being expanded,         interpolated and compared(!), with constant learning.

-   10) Electronic synchronisation:     -   each spindle rotor with its own (synchronous) motor plus         encoders,     -   Cooling fluid fed to the spindle rotor cooling thread through         the hollow motor shaft (with single clutch)

Tribivari Helps Itself by Fixing Itself Practically Single-Handedly, i.e.:

Tribivari is intelligent insofar as Tribivari with the mentioned (self-)diagnostic tools in the form of “self-diagnosis” firstly recognises, itself, if Tribivari changes due to wear, abrasion, dirtying and/or deposit formation, and can then adjust its operating behaviour on that basis via the described control tools, specifically this means that, for example at each operating point, as required by the user's process operating point in the particular situation,

a) the most appropriate gap values are set via PartCool or PartCool&Control, b) each optimal inner compression ratio is set via post-inlet and/or pre-outlet, c) and the most suitable rotor speed is set.

Based on the individual start state of this Tribivari system stored in the control unit, the current state (due to wear, abrasion and/or dirtying, deposit formation possibly changed) of Tribivari is taken into account in the algorithm of the control unit, as are also the current ambient conditions (hotter, colder, dirtied heat exchangers, etc.) and the currently desired operating requirements (i.e. in terms of volume flow, pressure level, but also allowable power consumption in the sense of avoiding expensive power peaks, etc.).

EXAMPLE 1

Tribivari uses its own (self-)diagnostic tools, i.e. by means of k₀ speed measurement and/or ΣΔρ measurement and/or algorithm-measured value comparison and/or Δφ rotor pair check and/or inverse cooling, etc., incl. any (evaluation) combination of these tools, to determine that the gap values have decreased in the outlet area, for example by deposit formation/dirtying. Tribivari can determine this via the algorithm in its own control unit, where individual guideline values (stored during the assembly of this Tribivari) are available for the different measured values and are stored with the respective links, relationships and interpretations, which are then compared with the incoming measured values. The control unit then adjusts the regulating tools as a regulation unit for this Tribivari system, for example in that PartCool reduces the cooling for the compressor housing via the outlet-side cooling fluid flow (9.1 a) and/or intensifies the two cooling fluid flows (9.2 and 9.3) to the spindle rotors. If these diagnostic results (here as an example: gap values at the outlet are reduced) were not known, there would be a risk that Tribivari would continue to cool the working space components and thus increase the risk of gap reduction (=crash). Thanks to this approach according to the invention via the mentioned (self-)diagnostic tools and regulating tools, these limits are now known for each operating point and use conditions, and Tribivari can not only be operated safely, but also in the optimum (in the sense of minimal energy requirement) range. At least by means of inverse cooling, it can even be determined individually for each spindle rotor which gap value has decreased, namely Δ21 or Δ3.1, in order accordingly to increase the relevant cooling fluid flow 9.2 or 9.3 according to the value tables present in the CU (for example previously calculated by FEM simulations).

EXAMPLE 2

Tribivari determines via its own (self-)diagnostic tools that the gap values have increased in the inlet area, for example due to abrasion/wear, noticeable by way of poorer compression behaviour. To compensate for (to “rescue”) this situation, for example, the cooling fluid flow 9.1 b at the compressor housing inlet area must be increased.

Based on “PartCool” as a self-diagnosis by means of:

-   -   k₀ speed measurement and/or ΣΔρ measurement combined with     -   inverse cooling (at least as a safety check against a crash         situation)

Content and Purpose:

Measurement of the compressibility of a compressor at zero flow rate (i.e. only “counteracting” the internal leakage and not expelling any conveyed medium at the outlet) for different rotor speeds within the scope of the Tribivari CU intelligence for the purpose of:

a) determining the actual achieved individual compression quality level at the end of assembly as a control and Okay approval (i.e. within the desired tolerance) stored in the system's own CU as a base output reference for continuous comparison during operation for the purpose of detecting a tendency and for prognosis displayed by extrapolation. b) Self-diagnosis during operation to detect changes (for example caused by wear, abrasion, dirtying, deposit formation, operational changes, for example in the process and/or in the environment, etc.) c) Preferably, the k₀ speed measurement is possibly also combined with ΣΔp measurement with the inverse cooling as an ongoing operational check for reliable crash avoidance by means of extrapolation.

Procedure for k₀ Speed Measurement:

If the inlet pressure is known, the outlet (over)pressure achieved is measured at the closed outlet for different rotor speeds and, thanks to PartCool, at defined(!) thermal situations**°° of the relevant (i.e. in particular the working space) compressor components (and the resultant individual gap conditions), and the quotient of outlet-to-inlet pressure gives the desired k₀ speed value for this rotor speed, and thus as a value table or as a functional representation:

y-axis=k ₀ value as quotient p _(a) /p _(i)

x-axis=rotor speed n _(R)

-   **°° Because, thanks to the CU intelligence by means of     PartCool&Control, the thermal situation, and, via the thermal     expansions of all working space components, the gap values can be     regulated and controlled in a targeted manner, in the case of the k₀     speed measurement, the individually defined component temperatures     are used to determine the particular compression quality level, and     the comparison with the base output reference values as well as     further measurements during operation reveals not only the current     state but also the changes:     -   i.e. self-diagnosis as well as prognosis and tendency. In         addition, the sufficient safety margin for crash avoidance is         determined by means of the inverse cooling, that is to say for         the stated working limits:         -   both safe crash avoidance     -   and         -   also the most efficient compression possible

Inverse cooling=simulation of a “wrong” (inverse) component cooling with a component temperature difference, as no longer occurs later during operation (because constantly monitored by the CU in this sense as well)

Both the k₀ speed measurement and the inverse cooling are repeatedly used during operation to detect changes within the lifetime of this compressor.

Simplification:

The inverse cooling is also executable via an algorithm stored in the CU as extrapolation of several “harmless” (in the sense of readily available) hot-fluid temperatures (preferably from the warm fluid reservoir (33), for example).

First as an overview: (then explained separately)

The following (self-)diagnostic tools belong (by way of example) to the Tribivari intelligence:

1) contact+withdrawal+fixation 2) inverse cooling 3) k₀ speed measurement 4) ΣΔp measurement 5) algorithm-measured values comparison 6) Δφ rotor pair check 7) combination & evaluation 8) . . . etc. . . . further (inherent) diagnostic tools can also be added here)

And the following regulating tools belong to the Tribivari intelligence (by way of example):

A) “PartCool”, also called “PartCool&Control” B) π_(i) adaptation C) FU speed variation

D) “ActionStep-ReactionCheck”

E) combination & evaluation

In Tribivari spindle compressors according to the invention at least the temperatures mentioned in FIG. 1 are measured, not only from the cooling fluid but also from the components. This is very easy with the compressor housing and in the frame-fixed inlet and outlet area, because these are stationary (frame-mounted) components. In the case of the rotating spindle rotors, the relationships between cooling fluid temperatures and rotor temperature for the various load states are stored in the control unit (25), so that the “defined temperature conditions” described hereinafter for the entire Tribivari spindle compressor are always known sufficiently precisely in the CU (25) or can be converted via interpolations (known geometry and material properties) with the resultant individual gap conditions also widely known.

These “defined temperature conditions” are an ongoing prerequisite for the correct use of these tools, which is ensured with sufficient accuracy thanks to the extensive temperature measuring points. (preferably similarly simple sensors such as those common in today's automobile construction industry and in widespread use)

Since the temperature conditions are never exactly the same, there is installed in the CU an algorithm for conversion to a uniform comparable state, which will henceforth be referred to by the term ‘defined temperature conditions’.

Separate cooling fluid temperature ranges at the reservoir (10) facilitate the achievement of defined temperature conditions by removing cooling fluid selectively for the relevant component.

The following (self-)diagnostic tools belong to the Tribivari intelligence (by way of example):

-   1) “Contact+Withdrawal+Fixation”: (This only occurs at the time of     assembly of the compressor stage) During assembly, each finished°*°     spindle rotor is introduced individually into the compressor housing     (1) until complete contact with its housing bore as so-called     “zero-gap”, that is to say touching, is achieved, wherein it must be     ensured that contact between the rotor and housing is as complete as     possible (check as appropriate by means of touch paste and rotate     slightly by hand to secure the rotor-housing contact), and therefore     the housing is preferably upright and the spindle rotor is     introduced from above. Because the (mean) inclination angle γ₂ or γ₃     between spindle rotor and housing bore is known, this rotor must now     be pulled out again in the rotor longitudinal axis direction over a     path distance Δz_(path) that can be directly calculated by     trigonometry and fixed between the inlet cover (16 or 17) and the     compressor housing (1) via adjustable distance/spacer plates (34 or     35) in order to satisfy the desired (mean) gap value Δ2.1 or Δ3.1     between spindle rotor (2 or 3) and the compressor housing (1),     wherein according to FIG. 6.a the following is true:     -   for the 2t rotor:

$\begin{matrix} {{\Delta \; z_{{Path}\; 2}} = \frac{\Delta \; 2.1}{\sin \left\{ \gamma_{2} \right\}}} \end{matrix}$

-   -   and for the 3t rotor:

$\begin{matrix} {{\Delta \; z_{{Path}\; 3}} = \frac{\Delta \; 3.1}{\sin \left\{ \gamma_{3} \right\}}} \end{matrix}$

-   -   It must be ensured that the components (i.e. the spindle rotor         in question and housing) have approximately the same component         temperature, which also must be logged or must be taken into         account when entering the data into the CU memory (also to be         entered into the CU). Advantageously, the gap size Δ2.1 and Δ3.1         can thus be set and logged in a targeted manner, which hitherto         has not been possible. In this case, a constant inclination         angle γ₂ or γ₃ is advantageous, however different inclination         angles are also possible in accordance with expansion laws in         the rotor longitudinal axis direction (i.e. according to         simulation of the compression process and heat dissipation of         the working space components), and therefore a mean inclination         angle can be applied, or the inclination angle that, according         to the simulation of the compression process and heat         dissipation of the working space components, primarily defines         the gap dimension Δ2.1 and Δ3.1.

-   *°*° finished spindle rotors: in the form of a rotation unit (40)     with the corresponding inlet cover (16 or 17) fully assembled,     wherein in particular the fixed bearing (10) is important for this     process.

-   2) Inverse Cooling:

In the “inverse cooling”, the gap dimensions between the working space components are measured and checked in that, at minimum (or even zero=standstill) speed of the spindle compressor,

-   -   a liquid (for example water) with steadily increasing fluid         temperature is conducted in a controlled manner through the         cooling fluid regions of each spindle rotor (2 or 3) preferably         in some sections via the transverse bores (29)     -   and or     -   a liquid with steadily decreasing fluid temperature is conducted         in a controlled manner through the various cooling fluid areas         of the compressor housing (1) preferably in some sections,         where the post-rotatability of the spindle rotors is checked         constantly, for example manually, at the time of assembly or for         self-diagnosis according to the invention in later operating         pauses by electronic motor pair-spindle rotor synchronisation.         Because of the different thermal expansions of these working         space components, the rotatability of the spindle rotors will be         terminated at a specific temperature level for this spindle         compressor machine, and the specific ACTUAL cold play values for         these spindle compressors are known on the basis of the known         material properties and the known geometry conditions and are         stored in the CU (25) for this spindle compressor.

Instead of using the first touching as “post-rotatability limit”, however, at least one ΔT_(BT) previously defined for this spindle compressor machine size should be established as the setpoint component temperature difference value and should ensure, via the simple (slow) rotatability monitoring, that there is no contact (touching) of the working space components. During later operation of this spindle compressor, the control unit (25) then knows how to adjust the particular cooling fluid flows of the working space components such that this ΔT_(BT) value is not exceeded, and therefore the crash can always be reliably avoided. This targeted regulation of the individual screw compressor components is also referred to below as “temperature control”.

In order to also be able to determine, in addition to the simple post-rotatability of the spindle rotors, the actual situation of the gap values and how this is affecting the compression behaviour of the Tribivari system, in accordance with the invention the inverse cooling is additionally performed by ΔT_(BT) value examination also linked with measures as described under “Combination & Evaluation”.

The ΔT_(BT) values, amongst other things in order to safeguard the crash avoidance, are thus considered to still be reliable, and component temperature differences checked multiple times by inverse cooling are continuously observed and preserved by the CU during operation in that the ΔT_(BT) values in question are not exceeded.

In particular, for higher compressor powers (for example over 75 kW power), it is useful to use the inverse cooling partially selectively in the rotor longitudinal axis direction by (as shown in FIG. 1) controlling the temperature selectively of individual areas both on the spindle rotor side and on the housing side using fluid, so that it is clearly recognisable how different the gap values in the rotor longitudinal axis direction are.

With these values, the “PartCool” can then be adjusted in a regulated manner during later operation in such a way that the gap values in each area are optimal: Optimal means that on the one hand a crash (i.e. gap reduction) is safely avoided, which is now finally possible thanks to the knowledge of the respective ΔT_(BT) values, and on the other hand the internal gap leakage can be monitored via the gap values managed by PartCool in accordance with the present simulation of the compressor process in such a way that the efficacy is maximised for precisely the current compression process.

For inverse cooling, the following case distinctions are expedient:

-   a) Assembly-related inverse cooling:     -   Here, at the time of assembly, the original start state is         recorded specifically for each spindle compressor after         contact+withdrawal+fixation, with the actual ΔT_(BT) values as         mounting ΔT_(BT) values, and is stored in its control unit (25).         In addition, linked measures are carried out as described under         “Combination & Evaluation” and these individual measured values         are stored in the CU for this Tribivari compressor. This process         forms the reference for possible changes (due to wear, abrasion,         dirtying, deposit formation, etc.) during later operation. -   b) Use-related inverse cooling     -   In the case of use-related inverse cooling, the assembly ΔT_(BT)         values (or similar in order to be able to determine the assembly         ΔT_(BT) values on the basis of a stored algorithm in the CU*°°*)         are preferably repeated and linked with Combination & Evaluation         to identify the current state of this Tribivari system.     -   The use-related inverse cooling is performed preferably during         breaks in operation, wherein the fluid with higher temperature         for the fluid flow areas of each spindle rotor comes from a warm         fluid reservoir (33). For this warm fluid reservoir (33), a         cooling fluid partial flow is either diverted uncooled during         operation and “warm parked” there or is selectively heated there         by electric heating generated there.     -   Of crucial importance here is the comparison of the currently         determined values with the previous values, in order to be able         to operate the Tribivari system optimally (i.e. avoiding a crash         and at the same time with best efficacy) and also identify         trends and enable forecasts.     -   *°°* If this process of drawing conclusions is adequately backed         up by sufficient experience, the use of warm fluid can be spared         later via extrapolation and interpretation. Nevertheless, it         sometimes helps to produce the defined temperature conditions. -   3) k₀ speed measurement:     -   In the case of the k₀ speed measurement, the instantaneous         compressibility of this spindle compressor machine is integrally         checked, wherein in particular the changes in the algorithm of         the control unit are evaluated in the sense of adaptation of the         PartCool and recognition of a trend.     -   Measurement of compressibility of a compressor at zero flow rate         (i.e. only “counteracting” the internal leakage and not         expelling conveyed medium at the outlet) for different rotor         speeds within the scope of the Tribivari CU intelligence for the         purpose of:         -   Determining the actually achieved individual compression             quality level at the end of the assembly as a control and             with OK approval (i.e. within the desired tolerance values)             in the inherent CU as base output reference stored for             constant comparison during operation for the purpose of             identifying a trend and for prognosis by extrapolation.         -   Self-diagnosis during operation to determine changes (for             example caused by wear, abrasion, dirtying, deposit             formation, operational changes, for example in the process             and/or in the environment, etc.)         -   Preferably, the k₀ speed measurement is possibly also             combined with total pressure difference measurement combined             with inverse cooling as an ongoing operational check for             safe crash avoidance by means of extrapolation.

Procedure for k₀ Speed Measurement:

If the inlet pressure is known at the closed outlet for different rotor speeds and thanks to PartCool under “defined temperature conditions” (Explanation=see above), the outlet (over)pressure) that has been reached is measured and the quotient of outlet pressure to inlet pressure gives the sought k₀ speed value for this rotor speed, and thus in the form of a value table or as a function representation, for example according to:

y-axis=k ₀ value as quotient p _(a) /p _(i)

x-axis=rotor speed n _(R)

-   **°° Because, thanks to CU intelligence, the thermal situation and,     via the thermal expansion of all working space components, also the     gap values can be selectively regulated and controlled by PartCool,     the compression quality level is determined via the individually     defined component temperatures for the k₀ speed measurement, and not     only the current state, but also the changes are identifiable via     the comparison with the base output reference values and other     measurements during operation: i.e. self-diagnosis and prognosis and     trend (by extrapolation).     -   In addition, the sufficient safety margin for crash avoidance is         determined via the inverse cooling—for the stated working         limits:     -   that is to say, both reliable crash avoidance and the most         efficient compression possible.     -   The k₀ speed measurement as well as the inverse cooling are         repeatedly used during operation to detect changes in the         service life of this compressor. -   4) integral pressure difference measurement, abbreviated as “ΣΔp     measurement”:     -   During the ΣΔp measurement, the current flow resistance of the         Tribivari compressor stage is measured by setting a selected         overpressure at “defined temperature conditions” with open inlet         and closed outlet in the outlet collection chamber (12) and by         measuring the reduction of the pressure in the outlet collection         chamber (12) for a selected period of time (for example 3         minutes) with very slowly rotating (for example less than 10         revolutions per minute) spindle rotors. This individual ΣΔp         measurement takes place for the first time at the end of the         assembly of each AirEnd spindle compressor and is stored in the         CU as a “Base reference”. During the course of operational use,         this ΣΔp measurement is repeated in the breaks in accordance         with a selected rhythm controlled by the CU and is compared both         to the base reference and to all follow-up measurements. From         this, a prognosis and trend can be deduced by extrapolation. -   5) Algorithm Measured Value Comparison:     -   During operation, there are many measured values, regulatory         actions and reactions in the CU (25) as well as various         evaluations. Based on the previously performed simulation         calculations as well as (FEM) model calculations of the relevant         compressor components, a steadily growing database is created,         which is continued with the constantly incoming data. In the CU         (25), these data are now continuously compared with one another         and interpolated using an algorithm, so that they are also         mapped (“modelled”) and stored for instances of use that are not         exactly the same as those currently occurring (for example,         higher conveyed gas inlet temperatures); the CU (25) delivers         the appropriate output signals (32.e).     -   Initially, due to the even smaller amount of data, the         comparison and interpolation will initially still be rough and         will be provided fuzzily with an increased level of uncertainty;         however, as the individual (rather specific inherent) database         grows steadily in the CU, this fuzziness will becomes less and         the machine will get increasingly better and smarter. -   6) Δφ rotor pair check: with Δφ as the angle of rotation between the     spindle rotors     -   In the case of the Δφ rotor pair check, the gap situation Δ3.2         between the spindle rotors (2 and 3) is checked individually for         each Tribivari system via the electronic motor pair-spindle         rotor synchronisation by means of the rotary angle sensors (20         and 21) for each shaft strand measuring the exact rotary angle         play and comparing it both with the base reference attained at         the time of assembly as well as the follow-up measured values,         and evaluating this in the sense of identifying trends and         providing a prognosis.     -   Procedure:     -   In the electronic motor pair-spindle rotor synchronisation, one         motor string (i.e. each spindle rotor with carrier shaft fixedly         connected to its drive motor rotor shaft) is then electrically         blocked (thus fixed) and the other motor string then checks the         remaining rotary angle Δφ as “remaining rotary angle play” and         stores this value. This measurement is repeated a number of         times for the entire spindle rotor pairing, and the maximum and         minimum values are stored and compared again (with base         reference and follow-up measured values), in order to (if the         values are correct, i.e. lie within the stored tolerance ranges)         set the mean value as setpoint specification for operation by         electronic motor pair-spindle rotor synchronisation. With the         electronic motor pair-spindle rotor synchronisation, it is         possible to determine for the spindle rotor pair via         -   reduced rotary angle play values a deposit formation or             dirtying         -   increased rotary angle play values an abrasive wear or             surface abrasion and wear     -   with appropriate feedback by CU, for example, to higher-level         maintenance and service stations. -   7) Combination & Evaluation:

The (self-)diagnostic tools mentioned are not only to be used and evaluated individually, but in particular also in combination. For example, the inverse cooling does not have to be driven until the first contact of the working space components as a check of the post-rotatability limit (also because of the risk of surface damage), in that the post-rotatability is ensured with a ΔT_(BT) of the inverse cooling defined previously in the CU (i.e. a clearly defined temperature level of the working space components) on the one hand, and on the other hand in that a ΣΔp measurement and/or k₀ speed measurement are/is performed, wherein the values then determined by these methods are compared with the basic reference and comparison values that are appropriate for this inverse cooling and are stored in the CU.

And the following regulating tools belong to the Tribivari intelligence (by way of example):

-   A) “PartCool”, also known as “PartCool&Control”:     -   The most important regulating tool is the individual control and         regulation of the cooling fluid flows for each component over         the relevant amount (mass flow) of the cooling fluid flow as         well as over the cooling fluid temperatures. This is not a         “bullish” control, but a control or regulation implemented by         the system response having a direct influence on the mentioned         PartCool parameters, hence the extended name of         “PartCool&Control”. Virtually all changes in the Tribivari         system as well as in the process and in the environment can be         compensated by PartCool&Control, because thanks to the data         stored in the CU for the particular work process (even if “only”         as extrapolation or interpolation of directly available data) as         well as the expansion behaviour and resulting gap values with         corresponding internal gap leakage values etc., the         corresponding compression behaviour of the Tribivari system can         be optimally adapted in each case. -   B) π_(i) adaptation:     -   Each work process experiences different conditions (for example         in respect of pressure and temperature values, volume flow,         ambient conditions, etc.), so that adjustments to the         compression process are desirable for the desired minimum         compression energy requirement. These adjustments also include         the “inner compression ratio” as the inner π_(i) value of the         compressor machine, which at first purely geometrically         describes the ratio of the inlet chamber volume to the outlet         chamber volume. The actual compression ratios (in particular the         temperatures and heat dissipation during compression) result in         the known over- and under-compression, which should firstly be         minimised as far as possible. The control unit of the Tribivari         system according to the invention can now adjust the internal         compression ratio of the current situation in an ideal manner at         any time via the regulation of partial gas flows via additional         partial outlet openings (15): This regulating tool in operation         is referred to as “π_(i) adjustment”. -   C) FU speed variation:     -   With this classic and long-known procedure, the spindle rotor         speed is adapted to the particular conditions by FU         ^((=frequency converter)) in particular with regard to the         currently desired conveyed medium volume flow: as is known,         almost proportional to the rotor speed. -   D) “ActionStep-ReactionCheck”:     -   Guided by the control unit at selected intervals (for example a         few minutes), small changes are made continuously, for example         in the cooling fluid flow to a working space component such as         the compressor housing and/or in the π_(i) adjustment, etc. It         is important that the ΔT_(BT) values stored in the CU for safe         crash avoidance are always observed (=important!). Based on the         constantly incoming measured values (in particular         temperatures), it can now be determined in the algorithm of the         CU whether this change has resulted in an improvement or         deterioration in the current compression process, in particular         determinable via the energy consumption (i.e. engine torques and         engine speeds and/or also only the motor current consumption).     -   Thus, “ActionStep-ReactionCheck” is a constant self-learning and         iterative method, which can be regarded both as a         (self-)diagnostic tool and as a regulatory tool, because the         system responses also reveal conclusions about the current state         of the Tribivari system. -   E) Combination & Evaluation:     -   The aforementioned regulating tools are not only to be used and         evaluated individually, but in particular also in combination.         Thus, for example, PartCool&Control and π_(i) adaptation via the         CU's own algorithm are always carried out in a coordinated         manner, preferably evaluated and performed in combination by         ActionStep-ReactionCheck. The storing of the results in the CU's         own database constantly increases the knowledge of this         Tribivari system and thus forms part of the Tribivari         intelligence.

In the case of the Tribivari intelligence, the evaluation of measures carried out is an essential precondition for the above-mentioned regulations.

This evaluation is carried out in accordance with the following features:

with the abbreviation “ES” as “Electronic motor pair-spindle rotor synchronisation” for example in respect of “ActionStep-ReactionCheck”: Improvements are noted when, at a working point at an existing pressure p_(B), the power requirement (which is even known at ES for each rotor) is reduced or minimal at a known speed, wherein the gap leakage and entropy balance are assessed in the algorithm of the CU via the temperature feedback (32.e) thanks to simulations and ongoing learning (writing of the “experiences” of this machine), so that the compr. efficacy can be specified. This is henceforth referred to as the objective of an efficient compression process for the current situation.

A volume flow measurement for the conveyed medium is generally too time-consuming, but would provide a nice facilitation if it were carried out or were available. Instead of improvements, of course, deteriorations in the compression behaviour also can be noted and are evaluated by the control unit, in order then to be able to initiate appropriate regulation measures (in particular by PartCool&Control etc.).

Advantageously, the cooling fluid flows are regulated by the CU in an application-specific manner for the particular situation in accordance with the algorithm stored in the CU and flexibly based on current experience by seeking the relevant optimum, wherein in particular the sufficient heat dissipation via a conventional external heat exchanger with advantageous temperature differences is taken into account.

This is the new Tribivari intelligence according to the invention and is not easily possible in the prior art.

The Tribivari system knows practically at any time with sufficient accuracy, how its individual status is currently (=how it is exactly, for example in respect of dirtying, deposit formation, state of wear, load capacity, temperature level, current gap values and compressibility etc.) in order to be able to use this knowledge to optimally perform the particular work process in the current situation(!) (optimally in the sense of most efficient compression in the current situation(!)).

In addition, thanks to the trend and forecast analyses mentioned, the CU will forward its status in good time to higher-level service and maintenance positions in order to permanently ensure the upkeep, care, maintenance and service as well as the availability of this system.

The Tribivari system is designed to be self-learning by continuously updating the analysis data individually for each CU under the particular process conditions and continuously optimising them further using ActionStep-ReactionCheck and storing them in the CU's own database.

Command Values for CU Intelligence: (!)=important (-)=less important

-   1) (!) Cooling fluid flow to 2t rotor     -   (by speed of its own cooling fluid delivery pump or the         regulating member) -   2) (!) Cooling fluid flow to the 3t rotor     -   (by speed of its own cooling fluid delivery pump or the         regulating member) -   3) (!) Cooling fluid flow to the housing=can be metered per section     (in particular for larger machines, for example >75 kW) -   4) (-) Cooling fluid flow to the side parts (actually only to the     outlet side part) -   5) (-) Cooling fluid flow to the lubricant (no longer with     electronic synchronisation) -   6) (!) Rotor speed (via FU=frequency converter:     -   possible without slip=synchro-motor) -   7) (!) Additional partial outlet openings as variable partial gas     flows

Measured Variables:

-   a) almost all temperatures     -   in particular practically all temp. differences ΔT for each         cooling fluid flow and at the conveyed gas plus lubricant         temperature as well as the component temperatures (in particular         on the housing and the side parts) -   b) rotor speed -   c) torque per rotor (with electronic synchronisation) -   d) each cooling fluid mass flow     -   (at least via the selectively regulated speed of the cooling         fluid delivery pump/characteristic possibly precisely) results         with ΔT the heat dissipation per working space component in each         working point at any time         Special features: -   1) The actual gap values Δ2.1 and Δ3.1 and Δ3.2 are detected at the     time of assembly of the compressor individually per machine, for     example by “inverse cooling” or “Contact+Withdrawal” and stored in     the CU, wherein these values during operation are then aligned with     the algorithm in the CU to regulate the different cooling fluid     flows for each working space component, such that on the one hand a     crash (i.e. gap reduction) is reliably avoided (depending on the     size of the machine, for example with about 15% safety reserve) and     on the other hand the gap values do not exceed a specified maximum     value (depending on the machine size, for example, about 1.5 times     the cold gap values recorded from the time of assembly).     -   This is because the CU is always aware of the compressor state         due to the management of the thermal situation and the thermal         expansion behaviour of the working space components stored in         the CU. -   2) Self-diagnosis and prognosis     -   for determining, recording and evaluating the current state, in         particular with electronic synchronisation to the speed         variation -   3) Process adjustment & ambient adjustment & temperature control &     compression adjustment via additional partial outlet openings -   4) k₀ speed measurement combined with inverse cooling for the     purpose of targeted determination of the current (i.e. corresponding     to the current state) individual PartCool with PartCool&Control

Definition of “working space”=space between inlet (11) and outlet (12) The working space is defined by the pair of spindle rotors (2 and 3) and the surrounding compressor housing (1) with the narrow (in the region of 0.1 mm and smaller) gap values Oxy of the various components. In the working space, the desired compression of the conveyed medium takes place via the working space components, i.e. spindle rotor pair (2 and 3) and compressor housing (1).

In addition, it is also true in accordance with the invention that the CU as a control unit (25) not only monitors, regulates and optimally manages the spindle compressor as described, but at the user location also not only communicates (for example Profibus system) with the entire system/plant controller via automation technology as industrial controller in the “process management technology”, but also actively participates therein, for example by managing/regulating the load management for the entire (at least in the case of this user) system, consisting of the individual compressor systems with their own CU (25) in each case, and therefore for example costly current peaks are avoided, wherein this then belongs to the term “Industry-4.0”. This also includes (preferably) at the same time (if the user agrees) also feedback to the supplier (or to the suppliers if there are more than one) regarding the current state of the compressor system with all individual systems including prognosis for further conduct with appropriate maintenance recommendation regarding the known diagnostic systems (for example vibration sensors, temperature profiles, etc.) with the corresponding evaluations (software). In addition, this also includes the constant and continuous adaptation to changed or changing process conditions, for example by deposit formation, dirtying, wear, etc., but also by external environmental conditions such as temperature level (for example warmer or colder environment), another desired pressure level, whereupon the intelligent CU system (25) responds by appropriate adjustment of the cooling water amounts, equalisation of the inner compression rate by means of additional partial outlet openings (15) etc., as well as all measures for self-diagnosis to determine the current state of this compressor in this application and prognosis over the further course with appropriate remedial action ranging from adjustment of the cooling fluid amounts up to a warning to the operator.

In the figures, instead of a subscript, merely a dot is inserted as index, so that for example R.F2 means R_(F2) and thus here denotes the root radius on the 2-toothed spindle rotor, wherein:

F stands for profile root K stands for profile head C stands for cooling WK stands for pitch circle 2 stands for the 2-tooth spindle rotor (2) 3 stands for the 3-toothed spindle rotor (3

FIG. 1 shows, by way of example, a 2-toothed spindle rotor (2) in longitudinal section with rotor geometry according to the invention and with cylindrical evaporator cooling bore (6) according to the invention and adapted positive-displacement profile root-base wall thickness w for the load-bearing root-base body (32) on the basis of the example of the 2t rotor with detail of the steam outlet (14) over a plurality of (balanced with the necessary cross-section Σ) transverse bores from the cylindrical evaporator cooling bore (6) with the radii values which are as follows:

R_(w2)<R_(D2)<R_(C2)

for the preferably blowhole-free profile pairing, the gas-conveying “external thread” (31) on the 2-toothed spindle rotor is located above the pitch circle line (37). As is known, the drive motor (18) consists of a motor rotor (mounted on the carrier shaft 4 for conjoint rotation) and a motor stator assembly with the electrical stator motor windings (shown by squared hatching), optional: extraction to the vacuum pump (29) starts at the neutral chambers (13) of the working space shaft bushings, in order to protect the bearings from the conveyed medium as necessary

FIG. 2 shows, by way of example, a cooling circuit with diversion of to cooling fluid (9) from the circuit, with cooling fluid injection (33) into the compressor working space per working point, targeted adjustment of the inner compressor volume ratio as iV value by additional partial outlet openings (15), with steam outlet (14) per working space component, i.e. housing (1) and rotor pair (2 and 3), shown in the inlet space (11)

the expansion valve, which is also shown, in the case of steam as the circulation medium, is preferably replaced via the simple height difference with the use of gravity as a “hydrostatic pressure difference” (the present illustration would then have to be adapted to the direction of the force of gravity).

The control unit (25) receives and processes various signals regarding the current operating requirements, the entire circulation system and in particular also from the compressor according to the invention, in order in particular to adjust the compressor components for each working point via the regulation members (38), such that the requirements are met in the best possible way—only with the control unit (25) can the system work reliably and efficiently (in practice a “New Intelligence”).

-   -   Referring to PCT/EP2015/062376=similar, but now improved by said         inventive features to meet the requirements of steam.

FIG. 3 shows, by way of example, a spindle rotor pair end-face section with an adaptation of the μ(z) values in the rotor longitudinal axis direction simplified as a projection in a common plane, because the rotor axes of rotation are at the angle alpha to each other and ought to be shown three-dimensionally, for the various positions E, S, V and L of FIG. 5

where the following is true for the μ(z) values:

$\begin{matrix} {{R_{K\; 2}(z)} = {{\mu_{2}(z)} \cdot {a(z)}}} \end{matrix}\mspace{14mu} \text{and:}\mspace{14mu} \begin{matrix} {{R_{K\; 3}(z)} = {{\mu_{3}(z)} \cdot {a(z)}}} \end{matrix}$

Adaptation of the μ(z) values for the rotor pairing according to the invention, preferably as 3:2 pairing to fulfil the following 3 core tasks:

-   -   maximising the nominal pumping capacity (based on the rotor pair         cross-sectional area, achieve the greatest possible scoop area)     -   with blowhole-free rotor pairing (minimise internal leakage)     -   with optimum use of the critical bending speed at each spindle         rotor, specific to their respective speeds

Design: For each of the 2t rotor and the 3t rotor with different cooling bore ø values R_(C2) and R_(C3) wherein the supporting steel shafts have not been shown for simplicity, and

different head strength distribution, since the root angle γ_(F2)>90°, so that the tooth cross-section of the 2-toothed spindle rotor (2) is slightly slimmer, without dropping below a minimum head width b_(K2) below (for example 5 mm).

This happens in such a way that the critical bending speeds per rotor (i.e. for 2t and 3t) match, so that the following is achieved for the spindle rotor pair:

-   -   The rotor pairing is without a blowhole, and therefore the         internal leakage is reduced.     -   Based on the illustrated rotor pair cross-section, this design         achieves significantly more scoop area and thus an increased         pumping capacity relative to the cross-section, which is sought         for steam compression.     -   Accordingly, the 2-toothed spindle rotor has the larger cooling         bore for heat dissipation during compression, so that the         component heat balance is improved in respect of heat absorption         and heat dissipation.     -   The 2t rotor has a speed 1.5 times higher than the 3t rotor and         accordingly it is embodied in accordance with the invention in         such a way that this 2-toothed spindle rotor achieves the more         rigid shaft thanks to R_(F2)>R_(F3) at reduced (by means of         γ₀>90°) mass, which is favourable for the increase of the         critical bending speed, because the 2-toothed spindle rotor also         has to rotate faster and accordingly has to be designed in         accordance with the invention with the higher critical bending         speed limit.     -   Accordingly, the slower 3t rotor has a lower bending critical         speed due to the lower bending stiffness, for which reason it         also rotates slower.     -   According to the invention, the rotor pair is now designed in         such a way that the critical bending speed at the 2t rotor is         1.5 times higher than the critical bending speed at the 3t         rotor, wherein the following is sought:

$\begin{matrix} {\omega_{\underset{2\text{-}{rotor}}{critical}} = {1.5 \cdot \omega_{\underset{3\text{-}{rotor}}{critical}}}} \end{matrix}\mspace{14mu} \text{with}\mspace{14mu} \begin{matrix} {\omega_{\underset{generally}{critical}} = \sqrt{\frac{c}{m}}} \end{matrix}$

bending critical speed generally as the square root of stiffness over mass

FIG. 4 shows an example as shown in FIG. 1 but for the 3t rotor with external profile conveying thread area below the pitch circle line (37), displacement profile area=where there is arranged the outer conveying thread (31) with profile teeth and tooth gap areas, which form the various working chambers as a series connection between the inlet and outlet and below the pitch circle line (37) ensure the blow hole-free compression.

FIG. 5 shows by way of example: rotors from FIG. 1 and FIG. 3 paired to show the overall rotor geometry and indicating the crossing angle alpha and the spindle rotor pairing with the engagement lens area engaging centrally with one another

FIG. 6 shows, by way of example, a total of 4 CAD illustrations, showing:

-   6a) a compressor housing (1) formed as a “pot housing”:     -   i.e. outlet-side closed bottom side and internal processing of         the working space from the open inlet side -   6b) Rotation unit:     -   each spindle rotor with carrier shaft, bearing, drive motor and         measurement system as a completely assembled and balanced unit         (40), ready for mounting and henceforth unchanged, shown here         only with the example of the 2-toothed spindle rotor, although         the same applies for the 3-toothed spindle rotor, wherein the         cylindrical flattened portion (27) at the 2t rotor inlet is not         shown. -   6c) assembly and play adjustment:     -   shown for both via separator plates (26) for the important rotor         head play relative to the housing, by way of example as a detail         for the head play Δ2.1 between 2-toothed spindle rotor head and         housing. The final clearance adjustment between rotor heads and         the housing is performed via separator plates (26), this being         illustrated by way of example as Δ2.1 in FIG. 6c for the         2-toothed spindle rotor head. -   6d) finished machine:     -   Both rotation units mounted in the pot housing plus frequency         converter (22 and 23) per motor incl. FU control unit (24),         which communicates with the control unit (25) for continuous         data exchange, which FU control unit in turn is connected to the         user process controller.     -   The motor windings of the two drive motors (18 and 19) are         protected against the conveyed medium for example by         vacuum-proof potting of the motor stator winding assemblies or         also by gap pots between the motor stator and motor rotor, etc.

The rotor internal geometry according to FIGS. 1 to 4 with the cylindrical evaporator cooling bore has not been included in FIG. 6, since this embodiment, as described, instead of applying for the described evaporator component cooling via a cylindrical evaporator cooling bore (6) according to FIG. 2, now applies for the option with separate cooling water flow as cooling water operation according to the industrial property right PCT/EP2016/077063, wherein in this embodiment a cylindrical internal rotor cooling is not required, because the internal rotor cooling shown in FIG. 6 is suffice.

This FIG. 6 shows:

-   -   good and reliable balancing for the rotary units, in particular         for the desired high speeds implemented in the case of steam to         about 350 m/sec as max. rotor head speed.     -   easy installation as a modular system, since different rotor         pair variants in the same housing geometry     -   targeted play adjustment via the separator plates (26) in order         to be able to compensate for the particular tolerance situation         (because all production parts have deviations/dimensional         differences within certain tolerances) caused by unavoidable         manufacturing tolerances “individually” (as precisely as         possible for these various components).     -   electron. synchronisation via (18) and (19) as drive for each         rotation unit     -   and with μC as a control unit for the intelligent cooling of the         components (as described above)

FIG. 7 shows by way of example: operating/working points as a basis (Excel) for the prior art=for turbo, improvement by the present invention by the higher ΔT with heat dissipation for t_(C)

-   -   more ΔT is desired for heat release below t_(C)         -   this cannot be done by one of today's turbos (already             working with 2 stages)         -   there must be a positive-displacement machine, which creates             the p/p pressure ratio         -   at the same time the machine must imperatively be formed as             an absolute/complete dry-running machine due to steam

FIG. 8 shows, by way of example, an illustration of the compression process in a pressure-enthalpy graph in the case of steam compression, showing the improvement due to the intensive evaporator heat dissipation during compression

-   -   prior art is shown as the dot-and-dash line (with labelling)     -   improvement according to the invention is shown as dashed line         (with labelling) compressing from         to

Purpose of the Presentation:

Prior art represented by turbo, which must work in two stages with intermediate cooling, as compared to the improvement of the invention, here referred to as “HydroCom” (abbreviated to HC)

Explanation of the Prior Art:

In order to isentropically compress^((Carnot)) from 8 mbar (to =4° C.) to 48 mbar (t_(c)=32° C.), intermediate cooling is indispensable for a 2-stage turbo because already isentropically from 8 mbar to 48 mbar there would already be a temperature rise of from 4° C. to approx. 200° C., without intermediate cooling.

Improvement According to the Invention:

Because of the enormous p/p pressure conditions with high isentropic exponent, the best-possible heat dissipation during compression must be ensured, which would otherwise lead to a fatally high (in the sense of increased compressor power) rise in compression temperatures, and therefore in accordance with FIG. 8 compression is performed practically almost at the dew line (i.e. better than isentropically), wherein the rotor pair cooling effort for to somewhat worsens the overall efficiency in refrigeration technology due to the diverted cooling fluid flow (9.2 and 9.3).

Thus, HC fulfils a stronger requirement profile according to FIG. 7 in that, in accordance with the invention, improved HC works from 7 mbar=2° C. to 96 mbar=45° C., thanks to efficient heat dissipation during compression.

FIG. 9 shows, by way of example: an Excel design table with example values for the parameter values for the positions E, S, V and L, stated by way of example, in the rotor longitudinal axis direction for the spindle rotor pair with individual values per spindle rotor, the indicated power specifications being only quite rough and constituting provisional reference values. Of course, both the selection of the named positions and the selection of other parameter values for the particular application-specific requirement profile are imperative.

Therefore, it should again be emphasised at this juncture that this is merely an example, showing only one of many possible design options for the rotor pair design according to the invention for demonstration purposes only.

For some applications, it may be favourable that the cylindrical evaporator cooling bore (6) is designed in a multi-stepped cylindrical form, as “terraces” so to speak, with the overflow edge as shown by way of example in FIG. 1.

Where reference is made here generally to cooling fluid, what is meant here is the R718 cooling fluid known from the field of refrigeration, which is naturally compressed at the chosen negative pressure as steam in the positive-displacement machine according to the invention, or in liquid form as cooling fluid (9) for component cooling by evaporation.

Terms such as “substantially”, “preferably”, and “the like”, and also “possibly”, which are understood to be imprecise, are to be understood such that a deviation by ±5%, preferably ±2%, and in particular ±1% from the normal value is possible. The applicant reserves the right to combine any features and also sub-features from the claims and/or any features and also sub-features from a sentence in the description in any manner with other features, sub-features or partial features, even beyond the features of independent claims.

In the different figures, parts that are equivalent with respect to their function are always provided with the same reference signs, so that they are generally described only once.

Since the lowest temperatures in the case of steam are above 0° C., the combination with the refrigerant R744 as CO₂ (as a 2-stage solution, also known as a “cascade”) is advantageous for lower temperature values (for example for deep freezing).

The invention relates to steam compression for refrigeration, air conditioning and heat pump technology, both for clockwise and anticlockwise (Carnot) cyclic processes. In order to improve the efficacy and operating behaviour at the same time with a greater pressure range, the present invention proposes a dry 2-shaft positive-displacement machine as spindle compressor, the spindle rotors (2 and 3) of which have a rotor pair centre distance which on the inlet side (11) is at least 10% greater than on the outlet side (12), and being driven by electronic motor pair (18+19)-spindle rotor (2+3) synchronisation, and each spindle rotor being provided with internal cooling, wherein the crossing angle alpha between the two rotor axes of rotation is formed in combination with the corresponding μ(z) value in the rotor longitudinal axis direction in such a way that a preferably cylindrical evaporator cooling bore (6) with minimal wall thickness w at the supporting root-base body (32) is formed for each spindle rotor under simultaneous consideration of the (preferably) blowhole-free profiling of the gas-conveying external thread (31) and critical bending speed “appropriate for the specific spindle rotor” and implementation of the inner volume ratio as iV value, wherein the inner volume ratio is adjusted during operation via additional partial output openings (15) and the gas-conveying external thread (31) in the case of a 2-toothed spindle rotor (2) is preferably formed with a cylindrical flattened portion (27) in the inlet region.

LIST OF REFERENCE SIGNS

-   1. Compressor housing with outer cooling areas and inlet-side     greater distance of the spindle rotor receiving holes than on the     outlet side, these bore axes being preferably intersecting (i.e.     with perpendicular distance zero) or also crossing (or skewed), with     external cooling fins for a cooling fluid flow rate (9.1) managed by     control unit (25), preferably with cooling fluid flow, for example     according to (9.1 a) and (9.1 b), in some sections in the rotor     longitudinal axis, wherein for larger rotor lengths (for     example >500 mm) a plurality of cooling fluid flow-through sections     are formed on the compressor housing, and the compressor housing     preferably is embodied as a so-called pot housing according to FIG.     6 a. -   2. Spindle rotor, preferably with 2-toothed gas-conveying external     thread (31), called a “2t rotor” for short, preferably made of an     aluminium alloy with good thermal conductivity (preferably above 150     W/m/K), fixed for conjoint rotation via support points (7) on a     steel shaft (4) and inside having a cylindrical evaporator cooling     bore (6) with radius R_(C2). -   3. Spindle rotor, preferably with 3-toothed gas-conveying external     thread (31), called a “3t rotor” for short, preferably made of an     aluminium alloy with good thermal conductivity (preferably above 150     W/m/K), fixed for conjoint rotation via support points (7) on a     steel shaft (5) and having inside a cylindrical evaporator cooling     bore (6) with radius R_(C3). -   4. 2t-rotor carrier shaft, connected to the 2t rotor for conjoint     rotation at radius R_(W2) (preferably pressed on) with central     cooling fluid supply bore (4.a), preferably integrally and at the     same time also shaft for the 2t drive motor (18) -   5. 3t rotor carrier shaft, connected to the 3t rotor for conjoint     rotation at radius R_(W3) (preferably pressed on) with central     cooling fluid supply bore (5.a), preferably integrally and at the     same time also shaft for the 3t drive motor (19) -   6. Cylindrical evaporator cooling bore with radius R_(C) and length     L_(C) for the corresponding spindle rotor, preferably with cooling     fluid guide grooves (16), cooling fluid distributor overflow grooves     (17) and support points (7) -   7. Support points as a rotationally fixed contact between spindle     rotors (2 and 3) and carrier shafts (4 and 5). -   8. Synchronisation toothing for the spindle rotor pair, also     rotating in the case of electronic synchronisation as fallback     transmission for emergency situations, for example power failure,     wherein the motors then automatically switch to generative operation     and only at the end (own power generation is no longer enough) does     the transmission prevent the spindle rotor contact.     -   As a fallback transmission, no lubricating oil is required,         wherein this toothing is realised with increased overlap ratio         (i.e. larger toothing bevel angle) so that the profile overlap         can be reduced by decreasing the tooth heights for smaller         sliding motions in the tooth engagement to reduce friction and         hence wear, wherein the tooth flanks preferably still receive a         dry-running coating as protection. -   9. Cooling fluid flow for cooling the compressor working space     components, i.e. rotor pair and housing, either diverted from the     circulation medium (34) according to the example in FIG. 2 or as a     separate cooling fluid flow shown in FIG. 6d generally, wherein, for     example the following is true: -   9.1 Cooling fluid flow to the compressor housing, for greater rotor     lengths (for example >500 mm) divisible into:     -   9.1 a cooling fluid flow through a portion of the compressor         housing (for example housing outlet side)     -   9.1 b cooling fluid flow through another portion of the         compressor housing (for example central area) -   9.2 cooling fluid flow to the 2t rotor -   9.3 cooling fluid flow to the 3t rotor -   10. Spindle rotor fixed bearing for receiving the gas pressure axial     forces and for exact fixing of each spindle rotor in the     longitudinal axis direction -   11. Conveyed gas inlet collecting space for the conveyed medium with     the gas pressure p₀ (for simplification, pressure losses in the     lines are initially ignored) -   12. Delivery gas outlet collecting space for the conveyed medium     with the gas pressure p_(C) (for simplification, pressure losses in     the lines are initially ignored) -   13. Neutral collection/buffer space per working space shaft passage     with reduced gas pressure with respect to the system pressure,     preferably for example generated by negative pressure/vacuum pump. -   14. Steam outlet via several transverse bores after a step with     radius R_(D2) or R_(D3) per rotor -   15. Additional partial outlet openings as diverted conveyed medium     outlet partial gas flow with a regulating member (pressure     difference valve) for adjusting the internal volume ratio -   16. Cooling fluid guide grooves with the radius R_(C) per     cylindrical evaporator cooling bore (6) with groove base surfaces at     an angle of inclination ψ, which is preferably 170°≤ψ≤180°, and the     cooling fluid guide grooves as a thread with the greatest possible     pitch=as in (31) -   17. Cooling fluid distributor overflow grooves (with undersized     cross-section) preferably in the groove bottom of (16) -   18 a. 2t drive motor as a direct drive for the 2t rotor, preferably     embodied as a synchronous motor -   19. 3t drive motor as a direct drive for the 3t rotor, preferably     embodied as a synchronous motor -   20 Rotary encoder for measuring the exact rotary angular position of     the motor 2t rotor carrier shaft (4) -   21. Rotary encoder for measuring the exact rotary angular position     of the motor 3t rotor carrier shaft (5) -   22. Frequency converter, referred to as “FU.2”, for the 2t drive     motor (18) -   23. Frequency converter, referred to as “FU.3”, for the 3t drive     motor (19) -   24. FU control unit, designated as “FU-CU”, for both frequency     converters FU.2 (22) and FU.3 (23), wherein the FU-CU directly     exchanges the operating data with the control unit (25). -   25. Control unit CU as a control and regulation unit with evaluation     of the current measured values and output, based thereon, of the     regulation signals for intelligent operation of the spindle     compressor with links and data preferably stored in the CU memory as     well as ever-learning dependencies between the incoming measured     values and the gap values according to previous simulation,     verification and ongoing experience, the control unit is connected     to FU-CU (24) as well as the user side with the process control     technology for its application system as well as factory control in     the sense of “Industry 4.0” -   26. Distance/spacer plates, preferably embodied as “separator     plates” for individual fixing of the spindle rotor in the rotor     longitudinal axis direction for targeted gap value adjustment as     Δ2.1 value on the 2t rotor (2) or as Δ3.1 value on the 3t rotor (3) -   27. Cylindrical flattened portion (as “cyl.” dimension specification     in FIG. 2) on the 2-toothed spindle rotor (2) over the radius     R_(KE2) on its rotor inlet side -   28. Circulation medium through the evaporator (35) for heat     absorption (as a core task in refrigeration technology) -   29. Vacuum pump for removal of foreign gases and for generation of     the necessary negative pressure for the steam cycle, preferably     sucking said gases into the neutral spaces (13) to protect the     (rotor) bearings. -   30. Water reservoir to compensate for water losses -   31. Gas-conveying external thread with preferably blowhole-free     profile rotor pairing to perform the compressor core task, namely to     transport the gaseous conveyed medium from the inlet (11) to the     outlet (12) and at the same time compress it -   32. Supporting root-base body with wall thickness w at each spindle     rotor (2 and 3) -   33. Cooling fluid injection into the working space of the compressor -   34. Circulating medium through the condenser (36) for heat output     (as a core task in heat pumps), circulating medium here is steam     (circulating through different states), but in principle also     suitable for other circulation media, for both clockwise and     anticlockwise Carnot processes -   35. Evaporator for the circulating medium, in which a quantity of     heat is absorbed. -   36. Condenser for the circulating medium, in which a quantity of     heat is output. -   37. Pitch circle line (abbreviation: WK) for the spindle rotor in     question -   38. Regulation members for selective adaptation of the volume flow     rate of the cooling fluid flow (9), managed by the control unit (25) -   39. Vibration sensors to determine modified residual unbalance     suggestions by different amounts of cooling fluid per spindle rotor     internal cooling -   40. Rotation unit per spindle rotor system, each fully assembled and     balanced, primarily consisting of:     -   spindle rotor (2 and 3)     -   carrier shaft (4 and 5)     -   synchronisation toothing (8)     -   bearing, with (10) as fixed bearing plus working space shaft         seals, for example with (13)     -   drive motor (18 and 19)     -   rotary encoder measurement system (20 and 21) thus, a total of         two rotation units (40) per spindle compressor 

1. A spindle compressor as a 2-shaft rotary positive-displacement machine, working without operating fluid in the working space, for conveying and compressing gaseous conveyed media, preferably steam, comprising a spindle rotor pair in a compressor housing (1) which has an inlet collection chamber (11) and an outlet collection chamber (12), characterised in that the centre distance of the spindle rotor pair at the inlet-side end is at least 10% greater than at the outlet-side end, in that each of the two spindle rotors (2, 3) is driven by an electric motor (18, 19), and an electronic synchronisation controls the electric motors (18, 19), and in that the spindle rotors (2, 3) rotate contact-free.
 2. The spindle compressor according to claim 1, characterised in that one spindle rotor (2) has two teeth, in that the other spindle rotor (3) has three teeth, and in that the electronic synchronisation is a 2 to 3 synchronisation.
 3. The spindle compressor according to claim 1, characterised in that each spindle rotor (2 or 3) has an internal cooling means, which preferably is embodied as a cylindrical evaporator cooling bore (6) of radius RC2 on the 2-toothed spindle rotor (2) or of radius RC3 on the 3-toothed spindle rotor (3).
 4. The spindle compressor according to claim 3, characterised in that the evaporator cooling bore (6) has an inner structure with at least one of the following features, preferably more than one: a) at least one cooling fluid guide groove (16), preferably with precise (deviation <1%) observance of the R_(C) value, in particular with a.1) groove base faces with angles of inclination ψ(z) with 170°≤ψ(z)≤180° as f(z) and/or a.2) the outlet region has a larger surface for heat transfer than the inlet region, b) cooling fluid distribution overflow grooves (17) c) support points (7) for non-rotational support on the corresponding carrier shaft (4 or 5) d) steam outlet (14) in the inlet chamber (11).
 5. The spindle compressor according to claim 1, characterised in that each spindle rotor system is embodied with the rotary unit (40) ready-assembled and balanced, and in that separator plates (26) are preferably provided for the final setting of the play between rotor heads and housing.
 6. The spindle compressor according to claim 1, characterised in that at least one vibration sensor (39) is provided and is connected to a control unit (25), and in that in the control unit (25) the supplied amount of the cooling fluid flow (9) is limited to the amount corresponding to a maximisation of the overall efficacy.
 7. The spindle compressor according to claim 2, characterised in that the critical bending speed of the 2-toothed spindle rotor is approximately (with a tolerance of preferably less than ±30%) 1.5 times higher than the critical bending speed of the 3-toothed spindle rotor (3).
 8. The spindle compressor according to claim 1, characterised in that the crossing angle alpha between the two spindle rotor axes of rotation in combination with the corresponding μ(z) value in the rotor longitudinal axis direction is such that, for each rotor, a cylindrical evaporator cooling bore (6) with minimal (that is to say appropriate for the particular tooth height in respect of material strength) wall thicknesses w is created on the supporting root-base body (32) (for example in accordance with the aforementioned position descriptions of E, S, V and L) under simultaneous consideration of the (preferably) blowhole-free profiling of the gas-conveying external thread (31) and critical bending speed “appropriate for the specific rotor spindle” and implementation of the inner volume ratio as iV value (as explained), wherein the gas-conveying external thread (31) is formed in the inlet region as a 2-toothed spindle rotor (2) preferably with cylindrical flattened portion (27).
 9. The spindle compressor according to claim 1, characterised in that the thermal situation for the working space components is regulated in an application-specific manner as basic step (as explained) during the component heat dissipation during operation to maintain the play values between avoidance of play reduction and excessive differences in the play values (as explained) and as FCT stage (as explained) during the component heat dissipation, to improve efficacy as diverted cooling fluid flow as separate cooling water flow via delayed evaporation with cooling fluid injection (33) into the compressor working space, preferably in the region of the inlet collection chamber (11), which is all regulated and controlled by the control unit (25).
 10. The spindle compressor according to claim 1, characterised in that each spindle rotor (2, 3) consists of an aluminium alloy and is pressed on to a steel shaft (4, 5) at the support points (7) for conjoint rotation, and in that the gas-conveying external thread (31) is only then produced and the spindle rotor (2, 3) has an inner structure that is already completed.
 11. The spindle compressor according to claim 1, characterised in that the inner volume ratio is adapted to the current operating conditions via additional partial outlet openings (15).
 12. The spindle compressor according to claim 1, characterised in that a steam outlet (14) directly to the inlet is provided.
 13. The spindle compressor according claim 1, characterised in that a cylindrical flattened portion (27) is provided at the inlet of the 2-toothed spindle rotor, in particular in that the gas-conveying external thread (31) in the case of the 2-toothed spindle rotor (2) has the cylindrical flattened portion (27) in the inlet region.
 14. The spindle compressor according claim 1, characterised in that the 2-toothed spindle rotor (2) is provided with an intermediate support, whereby a weight reduction, in particular also for a lower moment of inertia during start-up (or braking) alongside high flexural rigidity, is preferably achieved for example from fibre-composite material suitable for vacuum, for example in the form of a CFRP material.
 15. The spindle compressor according to claim 1, characterised in that at least one cooling fluid feed (9.2 and 9.3) is provided, and in that each spindle rotor has a cylindrical evaporator cooling bore (6), which is connected to the cooling fluid feed (9.2 and 9.3).
 16. The spindle compressor according to claim 1, characterised in that each drive has a hollow shaft, in that the cooling fluid feed (9.2 and 9.3) to the cylindrical evaporator cooling bore (6) of a drive is provided through this hollow shaft, and in that the bearings (10) are preferably formed as durable bearings, in particular grease-lubricated-for life hybrid bearings, all-ceramic bearings, or also magnetic bearings. 